Suspension mounting for the focussing device of cathode-ray tubes



April 8, 1952 D. JACKSON 2,591,820

- SUSPENSION MOUNTING FOR THE FOCUSING DEVICE 'OF CATHODE-RAY TUBES Filed Jan. 28, 1949 In ventor Patented Apr. 8, 1952 SUSPENSION MOUNTING FOR THE FOCUS-- SING DEVICE OF CATHODE-RAY TUBES Donald Jackson, Cambridge, England, assignor to Pye Limited, Cambridge, England, aBritish company Application January 28, 1949,. Serial No. 73,347 In Great Britain February 7", 1948' 9 Claims.

The present invention relates to a suspension mounting for the focussing device of a cathode ray tube, particularly for use in television receivers, whereby the focus coil or focussing magnet may be adjusted so that the raster may assume the desired position upon the screen of the tube.

According to the present invention, the focussing device is mounted so asto be laterally adjustable, with reference to the axis of the cathode ray tube, intwo directions at-right angles to each other. The centering of a television picture on the screen of the tube is thus effected by laterally moving the focussing device as distinct from ode ray tube, and upon which bracket member is mounted a support member which inturn supports the magnetic focussing device which. may be either a coil or a permanent magnet, through a. pin and slot connection or the like whereby it may be adjusted relative to the support member in a direction transversely with respect to the axis of the focussing device, the support member being also adjustably connected to the bracket member through a pin and slot connection so that it can be adjusted with respect thereto in a direction transversely with respect to the axis of the iocussing device and substantially at right angles to the direction in which the focussing device is adjustable on the support member. With this arrangement the focussing device can be adjusted in two directions at right angles transversely with respect to the neck of the cathode ray tube, when inserted through the bore of the focussing device, whereby the position of the rastor on the-screen may be adjusted.

The focussing device is urged by resilient means, such as a springer block of rubber or like material in one direction in the slots in the support member, a screw or equivalent means carried by a fixed part of the mounting separate from the focussing device being provided for moving the magnet relative to the support member against the action of said resilient means. Thus by turning this screw in one direction the focussing device can be moved transversely in one direction against the action of the resilient means, whilst by turning the screw in the opposite direction the resilient means moves the focussing device in the reverse direction tokeep-it in engagement with the adjusted position of the screw.

The support member is likewise urged either directly or indirectly by similar resilientmeans in one direction with respectto the bracket memher, a further screw or equivalent means being provided for moving the support member relative to the bracket member against the action of the said resilient means. By turning this second screw in one direction thesupport member, and consequently the focussing device carried thereby, is moved transversely with respectto the axis of the cathode ray tube in-a direction atright angles to the movement thereof produced by the first screw, whilst turning the screw in the opposite direction permits the resilient member to move the support plate, and the focussing device carried thereby, in the reverse direction. It is to be understood that the resilient means may bear on the support member or on the focussing device itself the supporting member being moved by the pin and slot connection.

A further feature of the invention consists in providing the focussing device with a sleeve which is longitudinally movable within the bore" of the magnet or focus coil in order to adjust the-width of the focussing gap of the focussing device.

The present invention will be more clearly understood by reference to the following description of one embodiment shown in the accompanying drawings, in which:

Fig. l is a sectional side elevation of the mount ing device sectioned on the line l-l of Fig. 2.

Fig. 2 is a front elevational View partly insection on the line lI--l l of Fig. 1.

Fig. 3 is a rear elevational view, and

Fig. 4' is a plan view partly cut away to show details of the mounting of the'focussing magnet.

According to'one embodiment of the invention in which the focussing device comprises an an- The ends of preferably all, and at least two, of

these screws [3 and 13a, pass through slots H in a metal plate constituting the support member l5,- both or all the slots extending in the same direction. In the arrangement shown the heads of the two screws like are used. to secure the focussing device to the supporting member l as shown in Fig. 1 to provide a pin and slot connection.

This support member I5 is provided with two pins [6 which project through two slots l! in a further metal plate constituting the bracket member 18, which slots extend in a direction at right angles to the direction of the slots M in the support member. The bracket member I8 is provided with a flange l9, around its periphery which extends in the direction of the magnet so as to surround the same. Through two threaded bosses 20, 2| fitted in apertures in this flange, which bosses are positioned respectively substantially in line with the two directions of movement of the focussing device and support plate, pass two screws 22, 23 the ends of which engage with the outer periphery of the magnet, or preferably with flat metal members 24 carried by the magnet or one of the clamping members 12, whereby, upon screwing in one or other of the screws 22 or 23, the magnet may be moved in one or other of two directions at right angles by reason of the pin and slot connections above described. Between the magnet 10, or its clamping members II and I2, and the inner surface of the flange l9, are also arranged two blocks of resilient rubber 25 and 26, in positions substantially diametrically opposite to the two screws 22 and 23, so that as the magnet is moved by screwing in one of the screws, the opposite rubber block is compressed. ,Upon releasing that screw the rubber block moves the magnet in the opposite direction to keep the flat metal member 24, in engagement with the s end of the screw.

. The flange I9- around the bracket member l8 may also serve for mounting the bracket member upon the chassis of the apparatus and, for this purpose, is conveniently provided with a flat section 190., as shown.

The adjusting screws 22 and 23 may be disposed for adjusting the magnet Ill, vertically and horizontally but are preferably arranged at such angles to the vertical and horizontal that by moving the magnet in these two directions the raster is moved substantially in the horizontal and vertical directions. Experiments show that these directions are approximately to the vertical and horizontal directions respectively.

The support and bracket members are, of course, apertured as indicated at 21 and 28 respectively to permit the neck of the cathode ray tube to pass therethrough. The bracket member 18 also carries a further apertured sheet metal stirrup bracket 29 therebehind which is fitted with a rubber grommet 30 for supporting the neck of the cathode ray tube indicated by the dotted lines 3 I. It will be noted that the mounting allows the focussing device to be moved in a plane in two directions mutually at right angles, the plane being transversely with respect to the axis of the annular focussing device and of the tube.

According to a further feature of the invention the rear annular magnet clamping member Ii is provided with a rearwardly extending tubular portion 32 within which can slide, in telescopic manner, a further tubular member 33 of magnetic material. By moving this member 33 into. or withdrawing it from the bore of the magnet the width of the focussing gap defined between the forward end of this tubular member 33 and the front clamping ring 12, may be varied. This adjustment is preferably effected by providing the outer tubular member 32, with a slot 34, inclined to the axis of the tube, with which a pin 35 projecting from the inner tubular member 33 engages so that, by rotating the inner tubular member, it is simultaneously moved longitudinally. The pin 35, is in the form of a screw which may be tightened to lock the inner tubular member 33, in the adjusted position. Preferably the slot 34, is curved so that greater leverage is obtained when the magnetic attraction is the greatest.

Whilst a particular embodiment has been described, it will be understood that various modifications may be made without departing from the spirit of the invention. For example, instead of providing the bracket member with a flange around its entire periphery, lugs may be provided for carrying the adjusting screws and as abutments for the resilient blocks.

I claim:

1. A suspension mounting for the magnetic focussing device for a cathode ray tube comprising, in combination, a bracket member having an attachment surface, a support member carried by said bracket member, an annular focussing device having an axis substantially parallel to said attachment surface, resilient means urging the focussing device in one direction transversely with respect to the axis of the focussing device, a

- screw carried by the bracket for moving the focussing device relatively to the support member in a direction opposing said resilient means, further resilient means urging the focussing device in a second direction transversely with respect to the axis of the focussing device and also transversely with respect to the direction in which the focussing device is adjustable on the support member, and a screw carried by the bracket for moving the support member relatively to the bracket against the action of said further resilient means.

2. A suspension mounting for the magnetic focussing device for a cathode ray tube comprising, in combination, a bracket member having an attachment surface, a support member carried by said bracket member, an annular focussing device having an axis substantially parallel to said attachment surface, pin and slot connections between the focussing device and the support member permitting adjustment of the focussing device relatively to the support member in a direction transversely with respect to the axis of the focussing device, pin and slot connections between said supporting member and said bracket permitting adjustment of the support member relatively to the bracket member in a direction at right angles to the direction in which the focussing device is adjustable on the support member, means restricting movement of the focussing device to said directions in a plane transversely with respect to the axis of the focussing device, resilient means urging the focussing device relatively to the bracket member in said directions and screws carried by said bracket member for moving the focussing device against the action of said resilient means in the directions permitted by the pin and slot connections, one of said directions extending at an angle approximately 30 to said attachment surface.

3. A suspension mounting for the magnetic. focussing device for a cathode ray tube comprising, in combination, a bracket member, a support member carried by said bracket member, an annular focussing device having a bore, connecting means between the focussing device and the sup:

port member permitting adjustment of the focussing device relatively to the support member in a direction transversely with respect to the axis of the focussing device, connecting means between said support member and said bracket permitting adjustment therebetween in a direction transversely with respect to the axis of the focussing device and transversely with respect to the direction in which the focussing device is adjustable relatively to the support member and a sleeve of magnetic material mounted for adjusting movement jointly with the fccussing device and for axial adjustment relative to the :"ocussing device within the bore thereof.

4. A magnetic focussing device for a cathode ray tube comprising an annular iocussing device having a bore and a tubular extension, a sleeve of magnetic material slidable and rotatable in said extension and extending Within said bore, an inclined slot in said extension, screw means on the sleeve extending through and movable along said slot, and means for tightening the screw means against the portions or" the extension adjacent said slot.

5. A suspension mounting for the magnetic focussing device of a cathode ray tube comprising, in combination, a bracket member, a support member, an annular focussing device having a bore and a tubular extension, pin and slot connections between the iocussing device and the support member permitting adjustment of the focussing device relatively to the support member in a direction transversely with respect to the axis of the focussing device, pin and slot connections between said support member and said bracket permitting adjustment therebetween in a direction transversely with respect to the axis of the focussing device and at right angles to the direction in which the focussing device is adjustable relatively to the support member, a sleeve of magnetic material slidable and rotatable in the extension on the focussing device and extending within said bore, a curved inclined slot in said extension and a pin on said sleeve and engaging said slot.

6. A magnetic focussing device for a cathode A ray tube, comprising an annular permanent magnet having two parallel end faces and an axial bore extending therebetween, a pole piece of magnetic material extending toward the axis of said magnet from one said end face, a member of magnetic material attached to the other of said end faces and having a tubular extension extending outwardly of said other end face coaxially with said bore, the inner diameter of said extension being less than the diameter of said bore, a sleeve of magnetic material slidable axially and rotatable in said extension so as to extend into said bore and form therein, jointly with said pole piece, a focussing gap, and pinand-slot helical guiding means for positively cor relating the rotary and sliding movements of said sleeve in said extension.

7. A magnetic focussing device for a cathode ray tube, comprising an annular permanent magnet having a bore and a tubular extension, a sleeve of magnetic material slidable and rotatable in said extension to form with said extension a pair of telescopic members and extending within said bore to form therein an annular focussing gap, an inclined slot in one of said telescopic members, and a pin carried by the other of said telescopic members and guidingly extending into said slot to enforce a redetermined ratio between the rotary and sliding movements of said sleeve in said extension, the slot being curved so as to progressively increase the said ratio as the sleeve is moved to narrow the focussing gap.

8. A suspension mounting for the magnetic focussing device for a cathode ray tube, comprising a bracket having a flat plate-like portion, an aperture in said portion through which the tube may extend, a flange extending normally to said portion at one side thereof, said flange forming an endless wall surrounding said portion, part of said flange being substantially flat to form an attachment surface for the bracket, a substantially plate-like apertured support member, pinand-slot connecting means by which said support member is guided for linear sliding movement on the plate-like portion of said bracket, an annular focussing device including a plate element extending substantially normally to the axis or" the focussing device, pin-and-slot connecting means by which said plate element is guided for linear sliding movement on the support member in a direction transverse to the movement of said member relative to the bracket, two resiliently compressible members interposed between said focussing device and portions of said flange for respectively urging said focussing device in the direction of said two pin-and-slot guiding means, two adjustment screws, and screwthreads supported by other portions of said flange for cooperation with the screws, said screws engaging said focussing device for adjustably moving the same against the urge of said compressible members in said two directions respectively.

9. A mounting as claimed in claim 8, in which the resiliently compressible members are constituted by deformable bodies of material having substantially the mechanical characteristics of soft vulcanised rubber.

DONALD JACKSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,200,039 Nicoll May 7, 1940 2,212,206 Holst et a1. Aug. 20, 1940 2,219,193 Mynall Oct. 22, 1940 2,224,933 Schlesinger Dec. 17, 1940 2,234,720 DeTar Mar. 11, 1941 2,416,687 Fry Mar. 4, 1947 2,418,487 Sproul Apr. 8, 1947 2,443,025 DeTar June 8, 1947 2,431,077 Pooh Nov. 18, 1947 2,433,682 Bradley Dec. 30, 1947 2,440,403 Jackson Apr. 27, 1948 2,442,975 Grundmann June 8, 1948 2,443,973 Asling June 22, 1948 2,456,399 Gethmann Dec. 14, 1948 2,501,516 Holden Mar. 21, 1950 2,521,061 Heisig Sept. 5, 1950 2,533,687 Quam Dec. 12, 1950 2,533,688 Quam Dec. 12, 1950 2,533,689 Quam Dec. 12, 1950 

